trimesh

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Trimesh is a pure Python 3.10+ library for loading and using triangular meshes with an emphasis on watertight surfaces. The goal of the library is to provide a full featured and well tested Trimesh object which allows for easy manipulation and analysis, in the style of the Polygon object in the Shapely library.

The API is mostly stable, but this should not be relied on and is not guaranteed: install a specific version if you plan on deploying something using trimesh.

Pull requests are appreciated and responded to promptly! If you'd like to contribute, here a quick development and contributing guide.

Basic Installation

Keeping trimesh easy to install is a core goal, thus the only hard dependency is numpy. Installing other packages adds functionality but is not required. For the easiest install with just numpy:

pip install trimesh

The minimal install can load many supported formats (STL, PLY, OBJ, GLTF/GLB) into numpy.ndarray values. More functionality is available when soft dependencies are installed, including convex hulls (scipy), graph operations (networkx), fast ray queries (embreex), vector path handling (shapely and rtree), XML formats like 3DXML/XAML/3MF (lxml), preview windows (pyglet), faster cache checks (xxhash), etc.

To install trimesh with the soft dependencies that generally install cleanly from binaries on Linux x86_64, MacOS ARM, and Windows x86_64 using pip:

pip install trimesh[easy]

If you are supporting a different platform or are freezing dependencies for an application we recommend you do not use extras, i.e. depend on trimesh scipy versus trimesh[easy]. Further information is available in the advanced installation documentation.

Quick Start

Here is an example of loading a mesh from file and colorizing its faces (nicely formatted notebook version of this example.

import numpy as np
import trimesh

# attach to logger so trimesh messages will be printed to console
trimesh.util.attach_to_log()

# mesh objects can be created from existing faces and vertex data
mesh = trimesh.Trimesh(vertices=[[0, 0, 0], [0, 0, 1], [0, 1, 0]],
                       faces=[[0, 1, 2]])

# by default, Trimesh will do a light processing, which will
# remove any NaN values and merge vertices that share position
# if you want to not do this on load, you can pass `process=False`
mesh = trimesh.Trimesh(vertices=[[0, 0, 0], [0, 0, 1], [0, 1, 0]],
                       faces=[[0, 1, 2]],
                       process=False)

# some formats like `glb` represent multiple meshes with multiple instances
# and `load_mesh` will concatenate irreversibly, load it as a Scene
# if you need instance information:
#   `scene = trimesh.load_scene('models/CesiumMilkTruck.glb')`
mesh = trimesh.load_mesh('models/CesiumMilkTruck.glb')

# is the current mesh watertight?
mesh.is_watertight

# what's the euler number for the mesh?
mesh.euler_number

# the convex hull is another Trimesh object that is available as a property
# lets compare the volume of our mesh with the volume of its convex hull
print(mesh.volume / mesh.convex_hull.volume)

# since the mesh is watertight it means there is a volume
# with a center of mass calculated from a surface integral approach
# which we can set as the origin for our mesh. It's perfectly fine to
# alter the vertices directly:
#   mesh.vertices -= mesh.center_mass
# although this will completely clear the cache including face normals
# as we don't know that they're still valid. Using the translation
# method will try to save cached values that are still valid:
mesh.apply_translation(-mesh.center_mass)


# what's the (3, 3) moment of inertia for the mesh?
mesh.moment_inertia

# if there are multiple bodies in the mesh we can split the mesh by
# connected components of face adjacency
# since this example mesh is a single watertight body we get a list of one mesh
mesh.split()

# facets are groups of coplanar adjacent faces
# set each facet to a random color
# colors are 8 bit RGBA by default (n, 4) np.uint8
for facet in mesh.facets:
    mesh.visual.face_colors[facet] = trimesh.visual.random_color()

# preview mesh in an opengl window if you installed pyglet and scipy with pip
mesh.show()

# transform method can be passed a (4, 4) matrix and will cleanly apply the transform
mesh.apply_transform(trimesh.transformations.random_rotation_matrix())

# axis aligned bounding box is available
mesh.bounding_box.extents

# a minimum volume oriented bounding box also available
# primitives are subclasses of Trimesh objects which automatically generate
# faces and vertices from data stored in the 'primitive' attribute
mesh.bounding_box_oriented.primitive.extents
mesh.bounding_box_oriented.primitive.transform

# show the mesh appended with its oriented bounding box
# the bounding box is a trimesh.primitives.Box object, which subclasses
# Trimesh and lazily evaluates to fill in vertices and faces when requested
# (press w in viewer to see triangles)
(mesh + mesh.bounding_box_oriented).show()

# bounding spheres and bounding cylinders of meshes are also
# available, and will be the minimum volume version of each
# except in certain degenerate cases, where they will be no worse
# than a least squares fit version of the primitive.
print(mesh.bounding_box_oriented.volume,
      mesh.bounding_cylinder.volume,
      mesh.bounding_sphere.volume)

Features

• Import meshes from binary/ASCII STL, Wavefront OBJ, ASCII OFF, binary/ASCII PLY, GLTF/GLB 2.0, 3MF, XAML, 3DXML, etc.
• Export meshes as GLB/GLTF, binary STL, binary PLY, ASCII OFF, OBJ, COLLADA, etc.
• Import and export 2D or 3D vector paths with DXF or SVG files
• Preview meshes using an OpenGL pyglet window, or in-line in jupyter or marimo notebooks using three.js
• Automatic hashing from a subclassed numpy array for change tracking using MD5, zlib CRC, or xxhash, and internal caching of expensive values.
• Calculate face adjacencies, face angles, vertex defects, convex hulls, etc.
• Calculate cross sections for a 2D outline, or slice a mesh for a 3D remainder mesh, i.e. slicing for 3D-printing.
• Split mesh based on face connectivity using networkx, or scipy.sparse
• Calculate mass properties, including volume, center of mass, moment of inertia, principal components of inertia, etc.
• Repair simple problems with triangle winding, normals, and quad/triangle holes
• Compute rotation/translation/tessellation invariant identifier and find duplicate meshes
• Check if a mesh is watertight, convex, etc.
• Sample the surface of a mesh
• Ray-mesh queries including location, triangle index, etc.
• Boolean operations on meshes (intersection, union, difference) using Manifold3D or Blender.
• Voxelize watertight meshes
• Smooth watertight meshes using Laplacian smoothing algorithms (Classic, Taubin, Humphrey)
• Subdivide faces of a mesh
• Approximate minimum volume oriented bounding boxes and spheres for meshes.
• Calculate nearest point on mesh surface and signed distance
• Primitive objects (Box, Cylinder, Sphere, Extrusion) which are subclassed Trimesh objects and have all the same features (inertia, viewers, etc)
• Simple scene graph and transform tree which can be rendered (pyglet window, three.js in a jupyter/marimo notebook or exported.
• Many utility functions, like transforming points, unitizing vectors, aligning vectors, tracking numpy arrays for changes, grouping rows, etc.

Additional Notes

• Check out some cool stuff people have done in the GitHub network.
• Generally trimesh API changes should have a one-year period of printing a warnings.DeprecationWarning although that's not always possible (i.e. the pyglet2 viewer rewrite that's been back-burnered for several years.)
• Docker containers are available on Docker Hub as trimesh/trimesh and there's a container guide in the docs.
• If you're choosing which format to use, you may want to try GLB as a fast modern option.